New command and a bug fix

1. When a new player joins, registers them in config as a default so that they can be ranked immediately.
2. Added a new command, /rank player group , using permission.rank<group> as a node. 
- New command is what setrankpb uses and is intended to integrate them to bypass the very annoying fixed broken nesting. If command is not accepted the "bug fix" allows set rank pb to rank players as soon as they join because otherwise when setrankpb tries to change the players rank, they aren't found and therefore it ends up creating a new player with the desired rank but the new player doesn't match the one in the game and the group is not changed. I basically integrated setrankpb with permissionsbukkit, i will be using this on my production server and i would like others to be able to as well, thanks - milkywayz